If memcg is enabled and no non-root memcg exists, all allocated pages
belong to root_mem_cgroup and go through root memcg statistics routines
which brings some overheads.
So for the sake of performance, we can give up accounting stats of root
memcg for MEM_CGROUP_STAT_CACHE/RSS and instead we pay special attention
to memcg_stat_show() while showing root memcg numbers:
as we don't account root memcg stats anymore, the root_mem_cgroup->stat
numbers are actually 0. So we fake these numbers by using stats of global
state and all other memcg. That is for root memcg:
nr(MEM_CGROUP_STAT_CACHE) = global_page_state(NR_FILE_PAGES) -
sum_of_all_memcg(MEM_CGROUP_STAT_CACHE);
Rss pages accounting are in the similar way.
Signed-off-by: Sha Zhengju <handai.szj@xxxxxxxxxx>
---
mm/memcontrol.c | 50 ++++++++++++++++++++++++++++++++++----------------
1 file changed, 34 insertions(+), 16 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 735cd41..e89204f 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -958,26 +958,27 @@ static void mem_cgroup_charge_statistics(struct mem_cgroup *memcg,
{
preempt_disable();
- /*
- * Here, RSS means 'mapped anon' and anon's SwapCache. Shmem/tmpfs is
- * counted as CACHE even if it's on ANON LRU.
- */
- if (anon)
- __this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_RSS],
- nr_pages);
- else
- __this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_CACHE],
- nr_pages);
-
/* pagein of a big page is an event. So, ignore page size */
if (nr_pages > 0)
__this_cpu_inc(memcg->stat->events[MEM_CGROUP_EVENTS_PGPGIN]);
- else {
+ else
__this_cpu_inc(memcg->stat->events[MEM_CGROUP_EVENTS_PGPGOUT]);
- nr_pages = -nr_pages; /* for event */
- }
- __this_cpu_add(memcg->stat->nr_page_events, nr_pages);
+ __this_cpu_add(memcg->stat->nr_page_events,
+ nr_pages < 0 ? -nr_pages : nr_pages);
+
+ if (!mem_cgroup_is_root(memcg)) {
+ /*
+ * Here, RSS means 'mapped anon' and anon's SwapCache. Shmem/tmpfs is
+ * counted as CACHE even if it's on ANON LRU.
+ */
+ if (anon)
+ __this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_RSS],
+ nr_pages);
+ else
+ __this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_CACHE],
+ nr_pages);
+ }
preempt_enable();
}
@@ -5445,12 +5446,24 @@ static int memcg_stat_show(struct cgroup *cont, struct cftype *cft,
struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
struct mem_cgroup *mi;
unsigned int i;
+ enum zone_stat_item global_stat[] = {NR_FILE_PAGES, NR_ANON_PAGES};
+ long root_stat[MEM_CGROUP_STAT_NSTATS] = {0};
for (i = 0; i < MEM_CGROUP_STAT_NSTATS; i++) {
+ long val = 0;
+
if (i == MEM_CGROUP_STAT_SWAP && !do_swap_account)
continue;
+
+ if (mem_cgroup_is_root(memcg) && (i == MEM_CGROUP_STAT_CACHE
+ || i == MEM_CGROUP_STAT_RSS)) {
+ val = global_page_state(global_stat[i]) -
+ mem_cgroup_recursive_stat(memcg, i);
+ root_stat[i] = val = val < 0 ? 0 : val;
+ } else
+ val = mem_cgroup_read_stat(memcg, i);
seq_printf(m, "%s %ld\n", mem_cgroup_stat_names[i],
- mem_cgroup_read_stat(memcg, i) * PAGE_SIZE);
+ val * PAGE_SIZE);
}
for (i = 0; i < MEM_CGROUP_EVENTS_NSTATS; i++)
@@ -5478,6 +5491,11 @@ static int memcg_stat_show(struct cgroup *cont, struct cftype *cft,
continue;
for_each_mem_cgroup_tree(mi, memcg)
val += mem_cgroup_read_stat(mi, i) * PAGE_SIZE;
+
+ /* Adding local stats of root memcg */
+ if (mem_cgroup_is_root(memcg))
+ val += root_stat[i] * PAGE_SIZE;
+
seq_printf(m, "total_%s %lld\n", mem_cgroup_stat_names[i], val);
}
--
1.7.9.5
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxx. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>